MHI launched Yahagi, the fifth Mogami-class frigate commissioned by the Japan Maritime Self-Defense Force (JMSDF), at a ceremony held at its facilities in Nagasaki City, June 23, 2022.
Credit: Kosuke Takahashi
While China and Russia continue to send ships and aircraft to the seas around the Japanese archipelago, Japan is relying on compact, missile-laden vessels to effectively deter its neighbors in the East China Sea and the Indo-Pacific region.
A planned fleet of 22 Mogami-class multirole frigates for the Japan Maritime Self-Defense Force (JMSDF) is part of this effort. Japan’s largest defense contractor, Mitsubishi Heavy Industries (MHI), has just launched the class’ fifth frigate.
The name Yahagi, the 133-meter-long vessel (pennant number FFM-5) went into the water at a ceremony held on June 23 at the company’s Nagasaki Shipyard and Machinery Works in Nagasaki Prefecture. Yahagi is expected to join the JMSDF in December 2023.
Equipped with compact hulls, JS Yahagi is building for about 47 billion yen ($ 346 million) under a contract awarded in February 2021, according to an MHI press release. As with the other ships in the class, the 3,900 tonne vessel will have a crew of around 90 (of which 10 are women), a width of 16.3 m and a hull draft of 9 m.
As China expands the size and capacity of its naval forces, Japan plans to defend the southwestern Nansei Islands, including the disputed Senkaku / Diaoyu Islands in the East China Sea, by increasing its patrol activities. The Senkaku / Diaoyu Islands are controlled by Japan, but also claimed by China and Taiwan.
A spokesman for JMSDF said Tokyo plans to build 10 Mogami-class ships under its Mid-Term Defense Program (MTDP) for the fiscal years 2019-23, which was approved in December 2018. With the MHI building two a year, JMSDF has plans to eventually place a total of 22 such frigates. The class’s first ship was formally commissioned in March 2022.
The JMSDF spokesman told The Diplomat that the new Mogami class will require fewer crew members and that compared to other frigate classes, the construction cost will be lower due to its compact size. This new concept of the frigate was forged amid the country’s rapidly aging population and shrinking pool of available citizens who are eligible to serve in the Japanese self-defense forces.
Powered by a combined diesel and gas (CODAG) propulsion system with two MAN 12V28 / 33D STC diesel engines and a Rolls-Royce MT30 gas turbine, the ships are expected to be able to achieve a top speed of at least 30 kt. The Mogami class marks the first part of a CODAG system on any JMSDF ship.
The armament on the frigates includes a BAE Systems 5-inch (127 mm) / 62-caliber naval pistol in the foredeck of the ship, two missile containers for a total of eight MHI Type 17 anti-ship missiles, also known as SSM-2, and a Raytheon 11-cell SeaRAM close -in weapons system (CIWS) capable of implementing RIM-116C Block 2 Rolling Airframe Missiles (RAMs).
The frigates will also be equipped with variable depth sonar and towed sonar systems for anti-submarine warfare (ASW) operations. They have six 324 mm torpedo tubes and NEC OQQ-25 variable depth sonar.
In addition to anti-air, anti-surface and ASW capabilities, the Mogami class is also designed to perform operations as a “mother ship” for an unmanned submarine (UUV) and an unmanned surface vessel (USV), both of which will see the first part of a Japanese frigate ever. This is to improve the UUV’s countermeasures (MCM) features.
A spokesman for the Japanese Ministry of Defense’s Agency for Acquisition, Technology and Logistics (ATLA) has confirmed to The Diplomat that the Mogami class will be equipped with MHI’s OZZ-5 MCM Autonomous Submarine (AUV) used for MCM operations as a UUV.
The French defense and electronics group Thales has provided MHI with its SAMDIS Synthetic Aperture Sonar (SAS) for integration on the OZZ-5 UUV. It is provided by MHI to JMSDF as part of the Defense Cooperation Agreement between the Direction Générale de l’Armement (French Defense Procurement Agency) and Japan’s ATLA.
SAMDIS is a high-frequency SAS payload in high resolution designed specifically to perform detection, classification and location of mining threats at sea.
The system operates an automatic detection and classification function to ease the operator’s workload when processing collected data.
Measuring 4 m long and 0.5 m wide with a displacement of 950 kg, the OZZ-5 UUV is equipped with Japan’s NEC-made low-frequency SAS and France’s Thales-manufactured high-frequency SAS together, which are designed to ensure a robust MCM -capacity for detecting and classifying various mining threats in a variety of environments.